Research Highlights

Research Highlights

A selection of highlights culled from publications by HAO staff.

Edge-enhanced images from near the core of the Mg II k line

Magnetic structure of the solar chromosphere-corona transition regions

The bulk of the emission from the plasma called "transition region" plasma originates from structures energetically connected both to the chromosphere and corona. This result resolves decades of debate and opens the door to measuring magnetic energy and its evolution in the corona using transition region emission lines.

scattering geometry of point P is shown in the observer's frame with projections of the magnetic field components in this frame

On single-point inversions of magnetic dipole lines in the corona

Prompted by a recent paper by Dima and Schad, we re-consider the problem of inferring magnetic properties of the corona using polarimetric observations of magnetic dipole (M1) lines.

Three panels display the active-regions' toroid patterns

Deciphering Deep-Origin of Active Regions From Analysis Of Magnetograms

Dikpati, et. al., derive magnetic toroids from surface magnetograms by employing a novel optimization method based on Trust Region Reflective algorithm. 

Root-Mean-Square Difference of the plasma drift between C/NOFS data and FORMOSAT-3/COSMIC DART/TIE-GCM ensemble data assimilation computed separately for the four geomagnetic longitudinal sectors

Data-Driven Ensemble Modeling of Equatorial Ionospheric Electrodynamics

A Case Study During a Minor Storm Period Under Solar Minimum Conditions: The dayside equatorial ionospheric electrodynamics exhibits strong variability driven simultaneously by highly changeable external forcings that originate from the Sun, magnetosphere, and lower atmosphere. 

Example spectro-polarimetric data of Active Region 12471 in the Fe I lines at 630.2 nm

Design of a Highly Efficient Polychromatic Full-Stokes Polarization Modulator for the CRISP Imaging Spectrometer

In 2014 HAO built a polarimetric modulator for the CRISP instrument on the Swedish 1-m Solar Telescope in La Palma, using the principles of polychromatic modulation previously developed by HAO scientists. This paper discusses the processes by which the modulator was designed, built, and tested. The modulator was installed and had been in use since 2015. It is working at close to optimal efficiency and has produced considerable scientific output.

Magnetic Bx component[nT] at five representative sites for 9/20/2002 - 10/10/2002

Modeling Diurnal Variation Magnetic Fields for Mantle Induction Studies

Accurate models of the spatial structure of ionospheric magnetic fields in the daily variation (DV) band (periods of approximately a few hours to a day) would enable use of magneto-variational methods for three-dimensional imaging of upper mantle and transition zone electrical conductivity. Constraints on conductivity at these depths, below what is typically possible with magnetotellurics, would in turn provide valuable constraints on mantle hydration and Earth’s deep water cycle.

Migrating Semidiurnal Tide during the September Equinox Transition in the Northern Hemisphere

Specified Dynamics Whole Atmosphere Community Climate Model with thermosphere-ionosphere eXtension (SD-WACCMX) simulations are used to investigate the solar migrating semidiurnal tide (SW2) around September equinox at middle to high latitudes in the Northern Hemisphere.

Combined temperature profiles from the Venus Thermosphere General Circulation Model (VTGCM) and observations near the equator (Lat = 0-30 N+S)

Planetary-scale Wave Impacts on the Venusian Upper Mesosphere and Lower Thermosphere

Venus’ atmosphere has a cloud layer (~40 km - ~70 km) that encompasses the whole planet that separates the lower atmosphere and upper atmosphere. Images of the clouds show planetary-scale wave patterns that exist from the equator to mid-latitudes and are thought to be a combination of Kelvin and Rossby waves. 

Effective diffusion coefficient

Effective vertical diffusion by atmospheric gravity waves

Han-Li Liu has observed that atmospheric gravity waves may transport heat and chemical species in the vertical direction.